The overall goal will be to develop MR and CT microscopy techniques capable of acquiring images of tissues with resolution on the order of 1-10 mum. MR microscopy is feasible with the use of high-field magnets and high-strength gradient systems, but the signal-to-noise ratio (SNR) often remains the greatest limitation to higher resolution. CT microscopy is possible using a newly acquired micro-CT instrument in the Candidate's department. The Candidate will develop the technology for MR and CT microscopy and apply it to the study of specific biological tissues (e.g., spinal cord, tumor vasculature, atherosclerotic plaque, trabecular bone and intervertebral disc), for the quantitative analysis of tissue micro-architecture under normal and pathologic conditions. The Candidate's career goals involve the development of his research skills in the area of MR and CT microscopy techniques as applied to medically significant tissue microstructures. Techniques he has worked on over the past few years, such as MR microscopy hardware, particularly cryo-cooled and micro-RF coil, will be further developed with reference to specific applications in collaboration with investigators at the University of Pennsylvania Medical Center who are active in research areas such as neurology and orthopedic surgery. The primary career development activities for the duration of the Mentored Quantitative Research Career Development Award will be Laboratory Research, Education, Professional Development, and Pursuit of Independent Support. The Laboratory Research comprises a Research Plan that advances micro-MRI and micro-CT technology as quantitative methods for characterizing tissue microstructure. The Education component involves mentor-guided study of the literature related to the Research Plan, in addition to courses, research seminars and a Research Ethics curriculum for training in the responsible conduct of research.